Linear alpha olefins (LAOs) are olefins with a chemical formula CxH2x, distinguished from other mono-olefins with a similar molecular formula by linearity of the hydrocarbon chain and the position of the double bond at the primary or alpha position. Linear alpha olefins comprise a class of industrially important alpha-olefins, including 1-butene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and higher blends of C20-C24, C24-C30, and C20-C30 olefins. Linear alpha olefins are very useful intermediates for the manufacture of detergents, synthetic lubricants, copolymers, plasticizers, and many other important products. Existing processes for the production of linear alpha olefins typically rely on the oligomerization of ethylene.
Processes for the oligomerization of ethylene utilizing a homogenous catalyst are widely known. For example, DE 43 38 414 C1 discloses a process for the oligomerization of ethylene to obtain linear alpha-olefins, where ethylene is catalytically converted in an empty tubular reactor utilizing a catalyst comprising a zirconium component and an aluminum component. The process is advantageously carried out in a continuous mode wherein gaseous and liquid outlet streams are obtained. The liquid outlet stream usually contains solvent, catalyst, dissolved ethylene and linear alpha-olefins. The catalyst can be preferably deactivated by caustic. Preferably, the deactivated catalyst is also extracted from the phase containing solvent, ethylene and alpha-olefins. DE 198 07 226 A1 discloses the deactivation of the oligomerization catalyst with an aqueous solution of sodium hydroxide (caustic), wherein the deactivated catalyst is transferred from the organic phase into the aqueous phase.
It is generally preferred to carry out the catalyst deactivation in a fast and effective manner to reduce or eliminate product degradation through various side reactions, ultimately affecting product purity. A disadvantage of known techniques is that during the catalyst deactivation and removal, hydrochloric acid (HCl) is formed, which can catalyze isomerization of linear alpha olefins. A further disadvantage of known catalyst deactivation processes includes the formation of organic chlorides and alkylated toluene byproducts.
Therefore, there remains a need for an improved method of catalyst deactivation for an olefin oligomerization catalyst that can overcome the above-described limitations of presently known methods.